title: The plastidic DEAD-box RNA helicase 22, HS3, is essential for plastid functions both in seed development and in seedling growth.
abstract: Plants accumulate large amounts of storage products in seeds to provide an energy reserve and to supply nutrients for germination and post-germinative growth. Arabidopsis thaliana belongs to the Brassica family, and oil is the main storage product in Arabidopsis seeds. To elucidate the regulatory mechanisms of oil biosynthesis in seeds, we screened for high density seeds (heavy seed) that have a low oil content. HS3 (heavy seed 3) encodes the DEAD-box RNA helicase 22 that is localized to plastids. The triacylglycerol (TAG) content of hs3-1 seeds was 10% lower than that of wild-type (WT) seeds, while the protein content was unchanged. The hs3-1 plants displayed a pale-green phenotype in developing seeds and seedlings, but not in adult leaves. The HS3 expression level was high in developing seeds and seedlings, but was low in stems, rosette leaves and flowers. The plastid gene expression profile of WT developing seeds and seedlings differed from that of hs3-1 developing seeds and seedlings. The expression of several genes was reduced in developing hs3-1 seeds, including accD, a gene that encodes the β subunit of carboxyltransferase, which is one component of acetyl-CoA carboxylase in plastids. In contrast, no differences were observed between the expression profiles of WT and hs3-1 rosette leaves. These results show that HS3 is essential for proper mRNA accumulation of plastid genes during seed development and seedling growth, and suggest that HS3 ensures seed oil biosynthesis by maintaining plastid mRNA levels.
authors.affiliation: Department of Cell Biology, National Institute for Basic Biology, Okazaki, 444-8585 Japan.
authors.forename: Masatake
authors.initials: M
authors.lastname: Kanai
authors.forename: Makoto
authors.initials: M
authors.lastname: Hayashi
authors.forename: Maki
authors.initials: M
authors.lastname: Kondo
authors.forename: Mikio
authors.initials: M
authors.lastname: Nishimura
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D060365:Chloroplast Proteins / Q000235:genetics / Q000378:metabolism; D053487:DEAD-box RNA Helicases / Q000235:genetics* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D009154:Mutation; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D010938:Plant Oils / Q000378:metabolism; D030821:Plants, Genetically Modified; D018087:Plastids / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D036226:Seedlings / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D012639:Seeds / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D014280:Triglycerides / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D060365:Chloroplast Proteins; D010938:Plant Oils; D012333:RNA, Messenger; D018749:RNA, Plant; D014280:Triglycerides; C587581:DEAD-box RNA helicase 22 protein, Arabidopsis; D053487:DEAD-box RNA Helicases
keywords: Arabidopsis; DEAD-box RNA helicase; Plastid; Seed development; Seed storage oil; Seedling growth